Anti-Brexit demonstrators wave EU and Union flags outside the Houses of Parliament in London, Britain, January 30, 2018.
In that sense, officials close to the negotiations suggest that Britain would, in any case, need to seek an extension to membership of the Customs Union, or quickly create a new arrangement that can swiftly mirror what now exists.
The Telegraph newspaper said Britain would tell Brussels it was prepared to stay in the union beyond the end of a post-Brexit transition period in 2020.
U.K. Prime Minister Theresa May is preparing a plan to solve the Irish border problem by keeping some European Union customs rules for years after Brexit, according to people familiar with the matter.
The EU and Dublin insist the treaty must lock in a backstop arrangement in case future customs arrangements do not remove the need for controls on the intra-Irish border.
A planned agreement allowing Irish students to continue to qualify for home fee status and student loan funding in the United Kingdom after Brexit is "discriminatory" and could imperil the UK's continued participation in European Union higher education programmes, experts have warned.More news: Trump Urges Senate to Confirm Gina Haspel as CIA Chief
More news: This cup has to be mine, says Neymar
More news: White House adviser: U.S. wants China trade deal as talks resume
Leo Varadkar met with Mrs May in Bulgaria on Thursday as part of a Western Balkans summit in the Bulgarian capital.
Meanwhile, the British cabinet continues to clash over the options open for a Northern Ireland-only agreement with the EU.
May was eager to find out what sort of response she can expect when European Union leaders assess progress on the Irish border issue at their summit in June, a senior European Union official said, asking not to be named because the discussions were private.
One of the 15 amendments that the Lords attached to the EU withdrawal bill calls for the government to explain what it is doing to remain in the (or a) customs union with the EU. The Irish Government has made it clear that it will veto a transitional deal if a hard border is imposed between it and Northern Ireland.
"The deadline, of course, for the withdrawal agreement is October - but if we're not making real, substantial progress by June, then we need to seriously question whether we're going to have a withdrawal agreement at all".
Addressing the problem of a potential hard border would "require more than just customs", the Taoiseach said. They are reinforced by HMRC signalling that neither of the options on the Cabinet table, a customs partnership or "max fac" could be ready by the end of 2020.
"Today's failure highlights the deep division at the heart of Government on the most basic of issues".